276 PALEONTOLOGY OF NEW JERSEY. 
but it is difficult to determine how far this feature may be reliable. Many 
of them are decidedly ovate, others so slightly so as to make the feature 
difficult of detection, while by far the most of the examples which I have 
seen would be called oval by anyone not expecting to question the form. 
The septa are closely arranged in some and in others somewhat distant, 
while they are not infrequently quite irregular in distance in the same indi- 
vidual, and sometimes do not extend the entire distance across the tube, but 
interfere with and terminate against the one below, so as to count irregular 
on opposite edges of the tube. In one specimen which comes to me from 
the Acad. Nat. Sci., Phila. this occurs twice within a length of an inch and 
a half, and all the septa in that distance are quite crowded. The septa 
have three lobes on each side of the tube and a small one on the ventral 
edge; while the siphonal lobe is simply bifid and the branches very small 
and short. The first dorsal lobe is much smaller than the others and 
directed somewhat inward toward the side or away from the dorsal edge. 
The second lobe is much larger and more numerously branched, while the 
third is still larger than the second as well as more complicated in structure 
and the ventral lobe quite small, short, and simple, but numerously digitate 
according to the size and age of the specimen. In detail the lobes and 
sinuses vary with size and age, but are almost as variable as the specimens 
are numerous, but in all the specimens which I have examined the second 
lobe is usually bilateral, nearly symmetrically so, and the sinuses in the 
lower half of the lobes are broad and rounded without serratures on their 
margins. 
Siphon situated just within the narrow edge of the tube and of rather 
large size. 
Shell marked on the outer portions in specimen of large size by undu- 
lations of growth indicating the outline of the aperture, and showing a 
considerable extension upward of the shell on both edges and a corre- 
sponding broad sinus on the sides, the extension on the siphonal side being 
much the longest. 
Formation and localities: In the Lower Green Marls throughout their 
extension in New Jersey and Delaware. Most common in Burlington 
County, New Jersey. Mullica Hill has also furnished many. The bluffs 
at Neversink, New Jersey, and Monmouth County have yielded some. 
